Tach

[Ole BlackBetty]

Ok, last week I was driving to work and tach stopped working. When I got to town, and stopped at stop sign, tried to take off when light turned green, truck didn't want to move. It was straining so I pulled shifter down to second and it came to life. E4od auto. Truck is not down shifting and always takes off in third gear! fast forward to this week, I bought a new tach sensor at stealership, for $80.00 ! Put it in and still no tach. So what could my problem be?

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[shawn deere]

Sounds like wiring problems to me. Volts good? Maybe check wiring harness when it goes through the firewall under the break pedal?

 

[catodd]

I had this same problem on my 92', but mine was intermittent, I replaced the tach sensor 3 times. I came across some instructions to remove the connector on the PCM and place some jumpers in the connector when I had no tach. The tach would work with the jumpers, telling I needed to replace PCM, replaced PCM and no longer have problem....I will try to find the instructions for jumpering PCM connector.

 

[Ole BlackBetty]

I had this same problem on my 92', but mine was intermittent, I replaced the tach sensor 3 times. I came across some instructions to remove the connector on the PCM and place some jumpers in the connector when I had no tach. The tach would work with the jumpers, telling I needed to replace PCM, replaced PCM and no longer have problem....I will try to find the instructions for jumpering PCM connector.

Thanks, please see what other info you can find.

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[Ole BlackBetty]

Sounds like wiring problems to me. Volts good? Maybe check wiring harness when it goes through the firewall under the break pedal?

I will see if I can check the tach wiring, thanks

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[catodd]

Info here

http://www.ford-trucks.com/forums/1371204-intermittent-tach-please-help.html

 

[FORDF250HDXLT]

never jump to conclusions.it costs money.

you lost power to the trans.this is why you lost 1st gear in the D position.the tach may also not work when one of the below fuses are blown.

check the I and the U locations here.

note the "pcm" relay.this is used for the e4od controller.if those fuses are ok,honk your horn (your testing the relay) and swap the horn relay there.the trans and the tach will work fine again once you replace either those 2 fuses or the relay.

to replace the relay latter,just grab one at the auto store and snap the mount tab off.


note:
if fuse U is blown,inspect the fuel bowl heater line and connector at the fuel filter!
if this shorts out,your trans has this issues.
listen:
the fuel heating element is not required.disconnect and cap off this wire.
both of my tucks have this circuit capped off to avoid the issue.

if you want the fuel heater that's ok.just do yourself a favor and run a devoted circuit for it.

haha.oh man i love having these albums with pics handy.this is so slick.

 

[catodd]

Mine also started out in 3rd gear when tach was not operating.

 

[Ole BlackBetty]

Well I discovered that fuse U was blown. Anybody in the market for a tach sensor for say 50.00 bucks ?

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[Diesile]

PM inbound

 

[FORDF250HDXLT]

that's why we start with the simple things first.did you find the reason it blew? did you unplug the fuel heater? (scratch that,i should call it what it is; fuel filter anti gel heating element. )

 

[Ole BlackBetty]

Haven't had time to replace it or check it out yet

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[Ole BlackBetty]

PM inbound

Hope I can figure how to read pm?

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[Diesile]

I'm probably a Dino., maybe there is no pm anymore.
Anyway I'd buy one of those tach sensors
Lorin